In the paper industry, several processes are known for the isomerization of 1-alkenes (alpha olefins) to result in internal olefins having a variety of uses. For example, internal olefins may be used in the preparation of alkyl succinyl anhydride (ASA), a paper size, by reacting them with maleic anhydride. Alkenes having more than four carbon atoms can be subjected to random isomerization using acids as catalysts (e.g. as described in J. Chem. Soc. Chem. Commun. 177 (1973), Barry et al.). However, isomerization processes utilizing acid catalysts are typically accompanied by oligomerization as a side reaction. These oligomers, which do not form adducts with maleic anhydride, lower the effectiveness of the ASA size. Moreover, oligomers may also contribute to the formation of deposits in the paper mill.
U.S. Pat. No. 6,355,855 (Nguyen et al.) generally describes the isomerization of 1-alkenes to internal alkenes in the presence of a catalyst composition comprising (i) salts of Group VIII transition metals and (ii) alkylaluminum compounds. The patent indicates that this combination isomerizes 1-alkenes to internal alkenes with only little formation of oligomers, however, the predominant internal alkene will typically be the 2-alkene, which in most cases will account for at least about 50%, particularly at least about 60%, and the formation of up to 70% or more of the internal alkenes.
U.S. Pat. No. 6,348,132 (Zhang) describes the sizing efficiency of ASA made from a mixture of internal alkenes with a substantially even distribution of isomers.
Thus, it would be desirable to have a process where alpha olefins can be isomerized to internal alkenes, such that the final mixture contains alkene isomers (i.e., 2-alkene, 3-alkene, 4-alkene, etc.) without the simultaneous production of substantial amounts of oligomers such as, for example, olefin dimers.